remove unused helper package

helper/main.go

-package helper
-
-import (
-	"math/rand"
-)
-
-func GenerateRandomString(length int) string {
-	const charset = "abcdefghijklmnopqrstuvwxyz0123456789"
-
-	// Generate random string
-	result := make([]byte, length)
-	for i := range result {
-		result[i] = charset[rand.Intn(len(charset))]
-	}
-	return string(result)
-}